Found 19th Mar 2016
Taken from GAME official page "Terms and Conditions: Your free £5 voucher will be issued on your till receipt when you purchase anything in store, or sent to you by email if you purchase online, from 19th March 2016 until 14th April 2016 only. Only one voucher will be provided for each transaction. The £5 voucher can only be redeemed when you spend over £50 (excluding the cost of any carrier bags purchased as part of the transaction) between 15th April 2016 and 27th April 2016 either instore or online.Vouchers issued via the website can only be redeemed via the website and vouchers issued instore can only be redeemed instore. Some stores may be closed over Easter, please check with your local store for details."
Instore and online purchases.